When removing loads from a roller conveyor, it is usually desirable to prevent the entire run of loads from bearing against the lead load at the discharge end of the conveyor so that the lead load can be easily removed. Various types of load spacing mechanisms have been used in the past for separating the lead load from the remaining loads on the conveyor. One type of device uses an actuating lever disposed at the discharge end of the conveyor that is connected by a mechanical linkage to a stop mechanism located at a point further upstream on the conveyor. When the lead load reaches the discharge end of conveyor, the weight of the load presses the actuating lever downward and causes the stop mechanism to move upward into the path of the next adjacent load. When the lead load is removed from the discharge end of the conveyor, the actuating lever returns to an normal position and the stop mechanism is retracted to allow the next load to move down the conveyor. Load separating mechanisms of this type are shown in the patent to vom Stein, U.S. Pat. No. 4,646,909, and Agnoff, U.S. Pat. No. 5,213,189.
Several drawbacks have been encountered with this type of load separating mechanism. One problem is the inherent complexity of the load separating mechanism. The load separating mechanisms typically have numerous components that complicate manufacture and assembly. Consequently, these types of mechanisms tend to be relatively expensive to produce. Further, the linkages which connect the actuating lever with the stop mechanism require periodic maintenance to maintain them in proper working order. Therefore, it is desirable to simplify the mechanism as much as possible to reduce costs and maintenance requirements.
Another drawback associated with the prior art load separating mechanisms is that the loads are released too quickly after a pallet is removed. The worker responsible for removing loads from the conveyor must have sufficient time to fully remove and dispose of the loads before the next load is released. In most prior art load separating mechanisms, the next load is released immediately as the lead load is lifted or partially removed from the discharge end of the conveyor. The patent to Agnoff addresses this problem by using a damper to delay the return of the actuating lever after a load is removed from the discharge end of the conveyor. This solution, however, further adds to the complexity of the mechanism and increases its cost.